There are a number of liquids that are stored at cold temperatures but require heating or warming before use. Examples include breast milk or infant formula for feeding babies and whole blood, plasma or serum for use in transfusion or infusion of patients. In both situations, it is important to heat or warm the liquid to a desired temperature, typically around 37° C., without overheating or uneven heating.
Breast milk or formula is generally stored in a refrigerator and heated from a storage temperature of about 4° C. to a body temperature of approximately 37° C. before being fed to the newborn baby. Lower heated milk or liquid feeding temperatures may be used in cases where parents are weaning their infants from a reliance on warmed milk or liquid.
One method of heating breast milk or formula is to use a microwave oven. However, microwave heating is known to result in hot spots within the volume of the liquid during the heating process. This can in turn lead to denaturing of nutrients present in milk.
Another method of heating breast milk or formula is to place a baby bottle containing the baby milk in an insulated cup containing hot water. This method of heating is generally slow since the walls of the baby bottle are usually bad conductors of heat. Furthermore, additional time and energy is required for heating of the water before the milk can be heated.
The methods of heating mentioned above are also not suitable when travelling or in remote areas such as battlezones or refugee areas, where access to appliances, work spaces and power is restricted. Additionally, both methods of heating require an approximation or manual measurement of the temperature of the liquid during heating.
Another type of liquid that requires heating before use is medical liquid for infusion such as for example blood, plasma or serum. Like milk, blood is generally stored at a temperature of approximately 4° C. Prior to use, the blood should be heated to body temperature of about 37° C. It is preferable that blood or plasma products be heated to body temperature as quickly as possible. It is also preferable for the blood heating system to be simple and straightforward to use. Some of these plasma products or other blood products can be frozen or partially frozen in storage.
Blood and blood products are often required in mobile hospitals, for example in battleground situations or refugee camps where power supplies are unpredictable and sometimes non-existent.
Another system of heating blood uses a heat exchanger coupled with two pumps. Blood and a suitable heat transfer liquid such as water are continuously pumped through the heat exchanger, wherein the water is separated from the blood but in heat transfer relationship therewith. The water is heated externally of the heat exchanger to maintain the blood at a preset desired temperature. This method of heating is generally not suited for outdoor conditions since the heat exchanger is bulky and difficult to operate.
Further, it is necessary at times to cool hot liquids quickly without liquid in certain zones being changed in state from liquid to solid.
The present invention seeks to provide a new heat exchange apparatus and method for heating or warming liquids.
It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.